1. Field of the Invention
The present invention relates to electrical connectors, and particularly to high density electrical connector assemblies for electrically interconnecting printed circuit boards.
2. Description of the Related Art
An arrangement for joining several printed circuit boards is to have one printed circuit board serve as a backplane and other printed circuit boards, called daughter boards, connected through the backplane. The backplane is usually provided with many connectors. Conducting traces in the printed circuit board connect signal pins in the connectors so that signals may be routed between the connectors. The daughter boards also contain connectors that are plugged into the connectors on the backplane. In this way, signals are routed among the daughter boards through the backplane.
Continued advances in the design of electronic devices for data processing and communications systems have placed rigorous demands on the design of electrical connectors. Specifically, electrical connectors for electrically connecting the backplanes and the daughter boards need to have higher densities and pin counts for design advances which increase integration of solid state devices and which increase the speed of data processing and communication. However, the increased density and pin counts unavoidably add the difficulties of mounting the electrical connectors to the backplanes and/or the daughter boards and of mating the electrical connector on the daughter board with the electrical connector on the backplane, and so on.
U.S. Pat. No. 5,975,921 issued on Nov. 2, 1999 discloses a high density electrical connector and is devoted to solve the problems of how to mount the high density electrical connector to a printed circuit board.
U.S. Pat. No. 6,220,896 issued on Apr. 24, 2001 is directed to a high density electrical connector which uses the stripline configuration to reduce the cross talk between signal contacts thereof.
U.S. Pat. No. 6,227,882 issued on May 8, 2001 discloses a high density electrical connector balancing the forces between electrical contacts thereof and of an electrical connector complementary therewith.
U.S. Pat. No. 6,299,484 issued on Oct. 9, 2001 discloses a high density electrical connector, a shielding plate of which is mechanically supported by and electrically connected with one of a column of electrical contacts thereof.
U.S. Pat. Nos. 6,179,663 and 6,206,729 issued respectively on Jan. 30, 2001 and Mar. 27, 2001 respectively disclose a high density electrical interconnect system having each of a first and a second electrical connectors thereof use multiple grounding methods to reduce or prevent spurious signals from interfering with high density contacts carrying high speed transmissions.
None of the electrical connector assemblies of the above-mentioned patents addresses the difficulties of mating the high density electrical connectors. Therefore, an improved electrical connector assembly is desired.
A major object of the present invention is to provide a high density electrical connector assembly comprising an electrical receptacle connector and an electrical header connector and reducing an insertion force needed to mate the electrical receptacle connector and the electrical header connector.
A high density electrical connector assembly in accordance with the present invention comprises an electrical receptacle connector mounted to a first printed circuit board and an electrical header connector complementary to the electrical receptacle connector and mounted to a second printed circuit board. The electrical receptacle connector comprises an insulative housing, a plurality of wafers accommodated in the insulative housing, and a plurality of inner printed circuit boards each comprising a mating portion and a mounting portion. Each wafer comprises a wafer body, a plurality of signal contacts mounted to one side of the wafer body, and a grounding bus mounted to the wafer body and each comprising a plurality of fingers extending along the one side of the wafer body and a plurality of tabs extending along the other side of the wafer body. The mounting portion of each inner printed circuit board is inserted between two adjacent wafers and electrically contacts with the signal contacts and fingers of one wafer and tabs of another adjacent wafer. The signal contacts, the fingers and the tabs are stagger with respect to each other.
The electrical header connector comprises an insulative housing and a plurality of wafers accommodated in the insulative housing for receiving therebetween and electrical engaging with the mating portions of the inner printed circuit boards of the electrical receptacle connector during the mating of the two electrical connectors. Each wafer comprises a wafer body, a plurality of signal contacts mounted to one side of the wafer body for electrically engaging with the inner printed circuit board, and a grounding bus mounted to the wafer body and each comprising a plurality of fingers and tabs for electrically contacting the inner printed circuit board. The signal contacts, the fingers and the tabs of the grounding buses are stagger with respect to each other.